Q1: Define Casting.
Ans: Casting is a manufacturing process in which molten metal is poured into a mould cavity and allowed to solidify to get the desired shape.
Q2: State some casting defects.
Ans: Casting defects are as follows:
- ➔ Blow holes
- ➔ Shrinkage defect
- ➔ Mis run
- ➔ Hot tears
- ➔ Mismatch or shift
- ➔ Drop
- ➔ Fins
- ➔ Porosity
Q3: What is Open Blow or Blow Holes?
Ans: Blow holes are smooth, round or oval holes formed in casting due to trapped gas inside the molten metal during solidification.
Q4: State the causes of Open Blow or Blow Holes.
Ans: The causes of blow holes are:
- ➔ Excess moisture in mould
- ➔ Poor venting of mould
- ➔ Improper melting of metal
- ➔ Low permeability of sand
Q5: State the remedies for Open Blow or Blow Holes.
Ans: Remedies for blow holes are:
- ➔ Proper drying of mould
- ➔ Improve venting system
- ➔ Use properly melted and cleaned metal
- ➔ Use good permeability sand
Q6: Define Shrinkage Defect as Casting Defect.
Ans: Shrinkage defect is a casting defect that occurs when the metal contracts during solidification and leaves empty spaces or cavities in the casting.
Q7: State the causes of Shrinkage Defect.
Ans: Causes of shrinkage defect:
- ➔ Improper feeding of molten metal
- ➔ Poor design of casting
- ➔ Lack of risers
- ➔ Uneven cooling rate
Q8: State the remedies for Shrinkage Defect.
Ans: Remedies for shrinkage defect:
- ➔ Proper use of risers
- ➔ Improve casting design
- ➔ Ensure uniform cooling
- ➔ Proper feeding of molten metal
Q9: Define Mis Run as Casting Defect.
Ans: Mis run is a casting defect in which molten metal solidifies before completely filling the mould cavity.
Q10: State the causes of Mis Run.
Ans: Causes of mis run:
- ➔ Low pouring temperature
- ➔ Thin sections in mould
- ➔ Poor fluidity of metal
- ➔ Slow pouring rate
Q11: State the remedies for Mis Run.
Ans: Remedies for mis run:
- ➔ Increase pouring temperature
- ➔ Improve mould design
- ➔ Increase metal fluidity
- ➔ Proper and fast pouring
Q12: Define Hot Tears as Casting Defect.
Ans: Hot tears are cracks formed in casting during cooling due to internal stresses when the metal is weak at high temperature.
Q13: State the causes of Hot Tears.
Ans: Causes of hot tears:
- ➔ Uneven cooling of casting
- ➔ Poor mould design
- ➔ High restraint in contraction
- ➔ Weak hot strength of metal
Q14: State the remedies for Hot Tears.
Ans: Remedies for hot tears:
- ➔ Improve casting design
- ➔ Ensure uniform cooling
- ➔ Reduce sharp corners in design
- ➔ Use proper alloy composition
Q15: Define Shift or Mismatch as Casting Defect.
Ans: Shift or mismatch is a casting defect in which the two halves of the mould are not properly aligned, causing a step or displacement in the casting.
Q16: State the causes of Shift or Mismatch.
Ans: Causes of shift or mismatch:
- ➔ Improper alignment of mould halves
- ➔ Loose fitting of mould box
- ➔ Incorrect pattern mounting
- ➔ Rough handling of mould
Q17: State the remedies for Shift or Mismatch.
Ans: Remedies for shift or mismatch:
- ➔ Proper alignment of mould
- ➔ Tight fitting of mould box
- ➔ Correct pattern setting
- ➔ Careful handling of mould
Q18: Define Drop as Casting Defect.
Ans: Drop is a casting defect in which a portion of the mould sand falls into the molten metal cavity and creates an unwanted projection in casting.
Q19: State the causes of Drop.
Ans: Causes of drop:
- ➔ Weak mould strength
- ➔ Poor ramming of sand
- ➔ Improper support of mould
- ➔ Rough handling
Q20: State the remedies for Drop.
Ans: Remedies for drop:
- ➔ Proper ramming of sand
- ➔ Improve mould strength
- ➔ Provide proper support
- ➔ Careful handling of mould
Q21: Define Fins as Casting Defect.
Ans: Fins are thin unwanted projections of metal formed at the joint of mould halves due to leakage of molten metal.
Q22: State the causes of Fins.
Ans: Causes of fins:
- ➔ Improper closing of mould
- ➔ Poor alignment of mould parts
- ➔ Excessive fluidity of metal
- ➔ Worn out pattern
Q23: State the remedies for Fins.
Ans: Remedies for fins:
- ➔ Proper alignment of mould
- ➔ Tight closing of mould
- ➔ Use good quality pattern
- ➔ Control metal fluidity
Q24: Define Porosity as Casting Defect.
Ans: Porosity is a casting defect in which small holes or voids are formed inside the casting due to trapped gas or shrinkage.
Q25: State the causes of Porosity.
Ans: Causes of porosity:
- ➔ Gas entrapment in molten metal
- ➔ Improper venting
- ➔ Moisture in mould
- ➔ Contaminated metal
Q26: State the remedies for Porosity.
Ans: Remedies for porosity:
- ➔ Proper venting of mould
- ➔ Use dry mould materials
- ➔ Clean molten metal
- ➔ Proper degassing of metal
